Reduced emissions metal melting furnace

Abstract

A vertical shaft furnace for melting non-ferrous metals, such as copper, aluminum, and their alloys, includes metal blocks disposed in an annular wall just beneath the charging section of the furnace. Preheated air is forced into the furnace shaft through openings in the wall of metal blocks to burn or oxidize substantially all the CO gas contained in the combustion gases rising from the melting chamber of the furnace. A pressurized plenum surrounding the shaft adjacent the charge opening is used to preheat ambient air which is then supplied under pressure to another plenum above the melting chamber where the preheated air is introduced into the shaft.

What is claimed is: 
     
       1. A vertical shaft furnace for melting non-ferrous metals comprising: a melting chamber in said furnace;   a burner means in said melting chamber for melting the metal charged to the melting chamber;   a charge opening in the shaft of said furnace disposed above said melting chamber for charging metal to be melted to the melting chamber;   means in the shaft of said furnace in proximity to said opening and above said melting chamber for introducing air into the shaft above the melting chamber; and   means for preheating the air introduced into the shaft above the melting chamber.   
     
     
       2. The shaft furnace of claim 1, wherein said air preheating means comprises a plenum surrounding said shaft. 
     
     
       3. The shaft furnace of claim 1, wherein said charge opening is closable by a loading door. 
     
     
       4. A vertical shaft furnace for melting non-ferrous metals comprising: a melting chamber in said furnace;   a burner means in said melting chamber for melting the metal charged to the melting chamber;   a charge opening in the shaft of said furnace disposed above said melting chamber for charging metal to be melted to the melting chamber;   means in the shaft of said furnace in proximity to said opening and above said melting chamber for introducing air into the shaft above the melting chamber, said air introducing means comprising a cylindrical section of said shaft located between the charge opening and the melting chamber, said cylindrical section having disposed therein a plurality of non-ferrous metal blocks forming a generally cylindrical wall, and openings in said wall through which the air is introduced into the shaft.   
     
     
       5. The shaft furnace of claim 4, wherein said air openings are formed by gaps between said blocks. 
     
     
       6. The shaft furnace of claim 4, wherein said air openings are formed by holes through said blocks. 
     
     
       7. The shaft furnace of claim 4, wherein said non-ferrous metal blocks are made of copper. 
     
     
       8. The shaft furnace of claim 4, further comprising a first plenum formed about said cylindrical section and means for supplying preheated air to said first plenum. 
     
     
       9. The shaft furnace of claim 8, wherein said preheated air supplying means comprises a second plenum disposed about the shaft of said furnace adjacent the charge opening and a first blower means connected to said second plenum for drawing air from the ambient atmosphere and pressurizing said second plenum. 
     
     
       10. The shaft furnace of claim 9, including damper means located in said shaft above said charging opening for increasing the pressure in said shaft. 
     
     
       11. The shaft furnace of claim 10, wherein said damper means comprises a second blower means and air jet means communicating between said shaft and said second blower means for introducing ambient air into said shaft in a direction opposite the flow of combustion gases from the melting chamber. 
     
     
       12. The shaft furnace of claim 11, wherein said air jet means are inclined downwardly toward the axis of the shaft furnace. 
     
     
       13. A vertical shaft furnace for melting non-ferrous metals comprising: a melting chamber in said furnace;   a burner means in said melting chamber for melting the metal charged to the melting chamber;   a charge opening in the shaft of said furnace disposed above said melting chamber for charging metal to be melted to the melting chamber;   means in the shaft of said furnace in proximity to said opening and above said melting chamber for introducing air into the shaft above the melting chamber, said air introducing means comprising a first plenum formed about said shaft; and   means for supplying preheated air to said first plenum comprising a second plenum disposed about said shaft adjacent the charge opening and communicating with said first plenum, a first blower means connected to said second plenum for drawing air from the ambient atmosphere and pressurizing said second plenum.   
     
     
       14. The shaft furnace of claim 13, including damper means located in said shaft above said charging opening for increasing the pressure in said shaft. 
     
     
       15. The shaft furnace of claim 14, wherein said damper means comprises a second blower means and air jet means communicating between said shaft and said second blower means for introducing ambient air into said shaft in a direction opposite the flow of combustion gases from the melting chamber. 
     
     
       16. The shaft furnace of claim 15, wherein said air jet means are inclined downwardly toward the axis of the shaft furnace. 
     
     
       17. The shaft furnace of claim 13, wherein said air introducing means further comprises a cylindrical section of said shaft located between the charge opening and the melting chamber, said cylindrical section having disposed therein a plurality of non-ferrous metal blocks forming a generally cylindrical wall, and openings in said wall through which the air is introduced into the shaft. 
     
     
       18. The shaft furnace of claim 17, wherein said air openings are formed by gaps between said blocks. 
     
     
       19. The shaft furnace of claim 17, wherein said air openings are formed by holes through said blocks. 
     
     
       20. The shaft furnace of claim 17, wherein said non-ferrous metal blocks are made of copper.